Recognition of Constancea is based on morphologic, cytologic, and molecular evidence for polyphyly of Eriophyllum if E. nevinii is included. Constancea has characteristics found in other, closely related x = 19 "helenioid" genera that are unusual or absent in the clade represented by Eriophyllum, Pseudobahia, and Syntrichopappus, such as leaves with well-developed petioles, phyllaries in more than one series and more than the number of ray florets, and pappus scales unequal or a longer pair opposite and ± equal. The previously suggested close relationship between Constancea and another coastal subshrub, E.staechadifolium, is untenable.